Introduction:

VXLAN (Virtual Extensible LAN) is a network virtualization technology that allows organizations to overcome the limitations of traditional VLANs by enabling the creation of large numbers of isolated Layer 2 networks. However, when connectivity issues arise between hosts on different VXLAN segments, it can impact network performance and stability. This report describes a scenario in which I had to troubleshoot an issue with VXLAN in a data center, identifying the root cause and implementing a resolution.

Scenario and Issue:

In our data center, we experienced intermittent connectivity issues between hosts on different VXLAN segments. This impacted the performance of applications and services running on those hosts, leading to degraded user experience and potential data loss.

Troubleshooting Steps and Resolution:

To identify the root cause and resolve the issue, I took the following steps:

1. Examined the network topology and VXLAN configuration on all related devices, including switches, routers, and VTEPs (VXLAN Tunnel Endpoints).
2. Used network troubleshooting tools like ping, traceroute, and Wireshark to identify connectivity patterns and isolate the problem. This helped to pinpoint the devices and configurations involved in the issue.
3. Discovered an incorrect VTEP configuration on one of the switches, causing sporadic connectivity issues between hosts on different VXLAN segments. The VTEP was not correctly mapping VXLAN VNI (Virtual Network Identifier) to the corresponding VLAN, leading to inconsistent connectivity.
4. Corrected the VTEP configuration by updating the VNI-to-VLAN mapping and verified that connectivity was restored between all affected hosts. Configuration example:

switch(config)# interface nve1
switch(config-if-nve)# member vni [VNI_NUMBER]
switch(config-if-nve)# vlan [VLAN_NUMBER]

5. Documented the changes and shared the findings with the team to prevent future issues related to VXLAN configuration.

Conclusion:

By identifying and correcting the VTEP configuration issue, we were able to restore stable connectivity between hosts on different VXLAN segments and improve overall network performance. This experience highlights the importance of thorough troubleshooting, accurate configuration, and effective communication within the team to ensure reliable and efficient network operations in a data center environment.